GPUs don't scale linearly unless you live somewhere where it is cold year round for free cooling, and you have a lot of space.

Sure they do - Just vent them outside. One 20" box window fan will move the heat of a LOT of GPUs outside (unless you live somewhere with an outside temperature already over 110F).

DAMN but I wish I lived somewhere other than one of the highest $-per-KW states right about now.

Where does the incoming air come from? From your air conditioner, right? Or, if no A/C, then it comes from the outside - which could easily be 90-110 degrees Fahrenheit. QED.

I was about to post the same thing, lol. I don't care how much air you can exhaust out your window from your mining room, it comes *IN* from somewhere. And in most locations the ambient air temp outside is going to get hot enough to kill the whole idea of just using a fan.

Where does the incoming air come from? From your air conditioner, right? Or, if no A/C, then it comes from the outside - which could easily be 90-110 degrees Fahrenheit. QED.

I was about to post the same thing, lol. I don't care how much air you can exhaust out your window from your mining room, it comes *IN* from somewhere. And in most locations the ambient air temp outside is going to get hot enough to kill the whole idea of just using a fan.

Exactly. This is why internal combustion engines in our cars stop working in the summer time. ...no wait...

You guys realize that 110 degrees Fahrenheit is "only" 43 Celsius, right? That's still over 30 degrees lower than the temperature my GPUs run at. With enough airflow, the heat will certainly still be removed so long as the heat isn't recirculated through the cards.

Where does the incoming air come from? From your air conditioner, right? Or, if no A/C, then it comes from the outside - which could easily be 90-110 degrees Fahrenheit. QED.

I was about to post the same thing, lol. I don't care how much air you can exhaust out your window from your mining room, it comes *IN* from somewhere. And in most locations the ambient air temp outside is going to get hot enough to kill the whole idea of just using a fan.

Where does it come from? No, not your air conditioner - You open... wait for it... Another window.Hot enough to kill the whole idea? Seriously? Do you folks live in Death Valley?

That article was more theory than proven practice. They only had 5 servers...in a tent, using way less power than something loaded with GPU's. Lets try to scale that up and see what happens.

There are *very* few places on earth where you can get away with cooling a dense DC with just ambient outside air. Trust me, Google and Facebook have looked very hard and written great articles about it. In the end they are forced to put DC's in places where the local temps get too hot, within the course of a year, to work with just outside air. We aren't talking about running a bunch of mining rigs just in the dead of winter. And when I say too hot it's not like I'm talking 135F. They end up using some form of energy input into the system to get the temps down. You would be surprised what Facebook can do by misting water into their fresh/recirc air. But that still takes power to pump! Not to mention the cost of the water!

And yes, it just so happens that I have had to design data centers in my career. Including power and cooling for them!

The key to the problem is the temperature delta. Sure ambient might "only" be 43 degrees C, but is that low enough to keep the server within tolerance after adding all the heat from the CPUs, RAM, SCSI cards, etc? Usually not.

I'm glad you don't design data centers for a living. You would kill a lot of hardware with your lack of knowledge.

Oh yes. Complete lack of knowledge. I've made national news for my "lack of knowledge" regarding hardware. If you took thermodynamics or fluid dynamics classes, you obviously flunked.

Funny you should mention it... I actually do. I work for a fairly large enterprise. Commercial data centers generally have other restrictions imposed on them or have other design concerns to work around. I certainly have a bit more freedom with my home rigs.

My 45 Ghash of equipment is currently putting out about 21.5KW of heat and they are crammed together in a more heat dense fashion than most data centers would ever allow (Amazon's EC2 possibly being an exception). I'm currently cooling everything with a standalone small household fan for each rig and 2 window fans. It gets into the high 90's and occasionally the low 100's here in the summer (desert climate). I used a small evap cooler last year during the summer because my current layout ends up recirculating a little of the air from one rig to the next. With the right building design and powerful fans, I wouldn't need an evap cooler at all. The fans on my reference cards are never running above 60 percent (right now, most of them are in the low 30's because the inlet air temp is still so cool).

In two weeks, I'll be migrating all of my rigs to a dedicated building in the back yard. In the summer, I won't need evap cooling if I want to run the fans a little high because I'll be exhausting ALL of the hot air and routing it properly. Can't wait to "kill a lot of hardware"!

The key to the problem is the temperature delta. Sure ambient might "only" be 43 degrees C, but is that low enough to keep the server within tolerance after adding all the heat from the CPUs, RAM, SCSI cards, etc? Usually not.

Of course it is. ...just not when you cram everything into a 1U case and flow hot air from one component to the next. Again, if this statement were true, we'd all have to shut down our cars in the summer.